This invention relates to aircraft flight director indicators and more particularly to simplified mechanisms for driving the command bars thereof.
Flight director indicators are used aboard aircraft to display to the pilot a unified presentation of the aircraft location and attitude in its spatial field of interest and to further indicate to the pilot the aircraft maneuvers required to reposition the aircraft to a desired attitude and displacement within the aforementioned field of interest. To accomplish this, the indicator, which is normally a panel mounted instrument, includes a front face having disposed essentially therein a shaped representation of the aircraft which is fixed with respect to the aircraft. Also located in the front face is an artificial horizon display maintained aligned with the actual horizon by a gyro as the aircraft maneuvers. The artificial horizon is additionally aligned with the indicator in such a manner that when the aircraft is straight and level the aircraft representation or fixed reference is parallel with respect to and aligned on the artificial horizon.
Command bars supported on the ends of struts which extend around the artificial horizon are driven by pitch and attitude command signals from the flight computer to present a realistic composite command display to the pilot when the command bars are viewed with respect to the fixed reference. The pilot obeys the command presented on his indicator by flying the fixed reference onto the command bars.
It is, of course, important in the aircraft instrument art that such instruments be as compact and simple as possible, while being suitable to perform their required functions. It is, thus, the main object of this invention to provide a simple, compact driving mechanism for the command bars of a flight director indicator. This is accomplished through the use of a command plate disposed behind the flight director indicator artificial horizon mechanism and having perpendicular axis which generally coincides with the flight director indicator longitudinal axis and about which the command plate is rotatably driven in accordance with roll commands. A pair of command bar struts are pivotally attached at diametrically opposed peripheral positions on the command plate and extend generally perpendicularly therefrom along the sides of the artificial horizon mechanism to terminate at their free ends in the command bars which are turned inward across the artificial horizon display so that in response to a zero command the command bars are aligned in close proximity with the fixed reference. The pivoted ends of the command bar struts are connected through a bail which is driven by a cam to position the command bar struts and hence the command bars in accordance with pitch command.